Cellular or wireless telecommunication systems have recently introduced a prepayment architecture that allows a subscriber to prepay for services. The advantage with prepaid services for the operator is that the operator obtains payment in advance saving costly collection services or having to obtain security such as credit card information from a subscriber. For the subscriber, the advantage is the subscriber pays as he uses the system avoiding basic monthly service charges when usage is low.
The current prepaid architecture in use and contemplated for cellular wireless telecommunication system stores the pre-payment made by a subscriber in a prepaid application server as a time duration value. When a prepaid subscriber initiates a call, the switching node of the wireless telecommunication system obtains the credit balance of the subscriber from the stored credit balance as a time interval value. The switching node determines the service charging rate for the call depending on the service the subscriber is requesting and applies this charging rate as a timer decrement. That is the timer set at the credit balance is decreased at a rate corresponding to the service requested. When the timer reaches zero time, representing a nil credit balance, then the call is cleared or ended by the switching node.
While the use of the prepaid service is gaining in popularity amongst subscribers and operators, there are two distinct and separate problems encountered by subscribers and operators of the prepaid system. The first to problem experienced by the subscriber is that there is no provision made by the telecommunication system that allows the subscriber to change or add new features during the call. For example, should a subscriber 1) wish to make a conference call, 2) change cell locations moving into a long-distance cell and/or 3) send a data, fax or short service message, the operator is not able to accommodate this change in service during a call because the operator has no mechanism in the prepaid architecture for revising the charging rate for the change in call services on a real-time basis. Consequently, the operator refuses to allow the subscriber access to services that cannot be billed for during the call.
The second problem with the prepaid billing systems is that no mechanism exists allowing the prepaid subscriber to roam between operators having roaming agreements or between operators having telecommunications equipment provided by different equipment suppliers using different proprietary billing protocols. Cellular wireless telecommunication networks currently employ multi-system mobile switching nodes center (MSC) networks that operate with different proprietary billing protocols. Consequently, it is difficult for operators to correlate billing information amongst these MSC networks. It is not possible at this time to correlate this information on a real time basis. Due to the differences in proprietary billing protocols between MSC networks, calls that are setup through several multi-system MSC's are rated according to the information logged in either the gateway MSC through which the call is setup to the public switching telephone network (PSTN) or the anchor MSC through which the call is delivered to the mobile station or prepaid subscriber.
Accordingly, there is a need for a prepaid service architecture that permits a prepaid subscriber to add or change service features during a call and allow the operator to charge for these revised service features. There is also a need to provide a standardized or common billing protocol amongst different operators and different equipment suppliers that permits for prepaid subscribers to access prepaid services while roaming.